.mask {
    width: 100%;
    height: 100%;
    position: fixed;
    top: 0;
    left: 0;
    background: rgba(0,0,0,0.3);
}

.mask .content {
    border-radius: 15px;
    text-align: center;
    width: 50%;
    height: 50%;
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    margin: auto;
    background-color: white;
}

#close {
    float: right;
}
th {
    text-align: center;
}

tr {
    text-align: center;
}